/*******************************************************************************

  Pilot Intelligence Library
    http://www.pilotintelligence.com/

  ----------------------------------------------------------------------------

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.

*******************************************************************************/


#include <string.h>

#include "AES.h"
#include "Crypto_utils.h"


namespace pi {
namespace crypto {


/*
 * S-box transformation table
 */
static uint8_t s_box[256] = {
    // 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, // 0
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, // 1
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, // 2
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, // 3
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, // 4
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, // 5
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, // 6
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, // 7
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, // 8
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, // 9
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, // a
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, // b
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, // c
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, // d
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, // e
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16};// f

/*
 * Inverse S-box transformation table
 */
static uint8_t inv_s_box[256] = {
    // 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f
    0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb, // 0
    0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, // 1
    0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e, // 2
    0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25, // 3
    0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92, // 4
    0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84, // 5
    0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06, // 6
    0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b, // 7
    0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73, // 8
    0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e, // 9
    0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b, // a
    0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4, // b
    0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f, // c
    0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, // d
    0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, // e
    0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d};// f



////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////

struct AES_Contex {
    AES_Contex() {
        Nb = 4;

        w = NULL;

        R[0] = 0x02;
        R[1] = 0x00;
        R[2] = 0x00;
        R[3] = 0x00;
    }

    ~AES_Contex() {
        if( w ) {
            delete [] w;
            w = NULL;
        }
    }


    /*
     * The cipher Key bit size
     */
    int K;

    /*
     * Number of columns (32-bit words) comprising the State. For this
     * standard, Nb = 4.
     */
    int Nb;

    /*
     * Number of 32-bit words comprising the Cipher Key. For this
     * standard, Nk = 4, 6, or 8.
     */
    int Nk;

    /*
     * Number of rounds, which is a function of  Nk  and  Nb (which is
     * fixed). For this standard, Nr = 10, 12, or 14.
     */
    int Nr;

    /*
     * Expended key
     */
    uint8_t *w;


    /*
     * Generates the round constant Rcon[i]
     */
    uint8_t R[4];

    uint8_t * Rcon(uint8_t i) {

        if (i == 1) {
            R[0] = 0x01; // x^(1-1) = x^0 = 1
        } else if (i > 1) {
            R[0] = 0x02;
            i--;
            while (i-1 > 0) {
                R[0] = gmult(R[0], 0x02);
                i--;
            }
        }

        return R;
    }



    /*
     * Addition in GF(2^8)
     * http://en.wikipedia.org/wiki/Finite_field_arithmetic
     */
    uint8_t gadd(uint8_t a, uint8_t b) {
        return a^b;
    }

    /*
     * Subtraction in GF(2^8)
     * http://en.wikipedia.org/wiki/Finite_field_arithmetic
     */
    uint8_t gsub(uint8_t a, uint8_t b) {
        return a^b;
    }

    /*
     * Multiplication in GF(2^8)
     * http://en.wikipedia.org/wiki/Finite_field_arithmetic
     * Irreducible polynomial m(x) = x8 + x4 + x3 + x + 1
     */
    uint8_t gmult(uint8_t a, uint8_t b) {

        uint8_t p = 0, i = 0, hbs = 0;

        for (i = 0; i < 8; i++) {
            if (b & 1) {
                p ^= a;
            }

            hbs = a & 0x80;
            a <<= 1;
            if (hbs) a ^= 0x1b; // 0000 0001 0001 1011
            b >>= 1;
        }

        return (uint8_t)p;
    }

    /*
     * Addition of 4 byte words
     * m(x) = x4+1
     */
    void coef_add(uint8_t a[], uint8_t b[], uint8_t d[]) {

        d[0] = a[0]^b[0];
        d[1] = a[1]^b[1];
        d[2] = a[2]^b[2];
        d[3] = a[3]^b[3];
    }

    /*
     * Multiplication of 4 byte words
     * m(x) = x4+1
     */
    void coef_mult(uint8_t *a, uint8_t *b, uint8_t *d) {

        d[0] = gmult(a[0],b[0])^gmult(a[3],b[1])^gmult(a[2],b[2])^gmult(a[1],b[3]);
        d[1] = gmult(a[1],b[0])^gmult(a[0],b[1])^gmult(a[3],b[2])^gmult(a[2],b[3]);
        d[2] = gmult(a[2],b[0])^gmult(a[1],b[1])^gmult(a[0],b[2])^gmult(a[3],b[3]);
        d[3] = gmult(a[3],b[0])^gmult(a[2],b[1])^gmult(a[1],b[2])^gmult(a[0],b[3]);
    }



    /*
     * Transformation in the Cipher and Inverse Cipher in which a Round
     * Key is added to the State using an XOR operation. The length of a
     * Round Key equals the size of the State (i.e., for Nb = 4, the Round
     * Key length equals 128 bits/16 bytes).
     */
    void add_round_key(uint8_t *state, uint8_t *w, uint8_t r) {

        uint8_t c;

        for (c = 0; c < Nb; c++) {
            state[Nb*0+c] = state[Nb*0+c]^w[4*Nb*r+Nb*c+0];
            state[Nb*1+c] = state[Nb*1+c]^w[4*Nb*r+Nb*c+1];
            state[Nb*2+c] = state[Nb*2+c]^w[4*Nb*r+Nb*c+2];
            state[Nb*3+c] = state[Nb*3+c]^w[4*Nb*r+Nb*c+3];
        }
    }

    /*
     * Transformation in the Cipher that takes all of the columns of the
     * State and mixes their data (independently of one another) to
     * produce new columns.
     */
    void mix_columns(uint8_t *state) {

        uint8_t a[] = {0x02, 0x01, 0x01, 0x03}; // a(x) = {02} + {01}x + {01}x2 + {03}x3
        uint8_t i, j, col[4], res[4];

        for (j = 0; j < Nb; j++) {
            for (i = 0; i < 4; i++) {
                col[i] = state[Nb*i+j];
            }

            coef_mult(a, col, res);

            for (i = 0; i < 4; i++) {
                state[Nb*i+j] = res[i];
            }
        }
    }

    /*
     * Transformation in the Inverse Cipher that is the inverse of
     * MixColumns().
     */
    void inv_mix_columns(uint8_t *state) {

        uint8_t a[] = {0x0e, 0x09, 0x0d, 0x0b}; // a(x) = {0e} + {09}x + {0d}x2 + {0b}x3
        uint8_t i, j, col[4], res[4];

        for (j = 0; j < Nb; j++) {
            for (i = 0; i < 4; i++) {
                col[i] = state[Nb*i+j];
            }

            coef_mult(a, col, res);

            for (i = 0; i < 4; i++) {
                state[Nb*i+j] = res[i];
            }
        }
    }

    /*
     * Transformation in the Cipher that processes the State by cyclically
     * shifting the last three rows of the State by different offsets.
     */
    void shift_rows(uint8_t *state) {

        uint8_t i, k, s, tmp;

        for (i = 1; i < 4; i++) {
            // shift(1,4)=1; shift(2,4)=2; shift(3,4)=3
            // shift(r, 4) = r;
            s = 0;
            while (s < i) {
                tmp = state[Nb*i+0];

                for (k = 1; k < Nb; k++) {
                    state[Nb*i+k-1] = state[Nb*i+k];
                }

                state[Nb*i+Nb-1] = tmp;
                s++;
            }
        }
    }

    /*
     * Transformation in the Inverse Cipher that is the inverse of
     * ShiftRows().
     */
    void inv_shift_rows(uint8_t *state) {

        uint8_t i, k, s, tmp;

        for (i = 1; i < 4; i++) {
            s = 0;
            while (s < i) {
                tmp = state[Nb*i+Nb-1];

                for (k = Nb-1; k > 0; k--) {
                    state[Nb*i+k] = state[Nb*i+k-1];
                }

                state[Nb*i+0] = tmp;
                s++;
            }
        }
    }

    /*
     * Transformation in the Cipher that processes the State using a non­
     * linear byte substitution table (S-box) that operates on each of the
     * State bytes independently.
     */
    void sub_bytes(uint8_t *state) {

        uint8_t i, j;
        uint8_t row, col;

        for (i = 0; i < 4; i++) {
            for (j = 0; j < Nb; j++) {
                row = (state[Nb*i+j] & 0xf0) >> 4;
                col = state[Nb*i+j] & 0x0f;
                state[Nb*i+j] = s_box[16*row+col];
            }
        }
    }

    /*
     * Transformation in the Inverse Cipher that is the inverse of
     * SubBytes().
     */
    void inv_sub_bytes(uint8_t *state) {

        uint8_t i, j;
        uint8_t row, col;

        for (i = 0; i < 4; i++) {
            for (j = 0; j < Nb; j++) {
                row = (state[Nb*i+j] & 0xf0) >> 4;
                col = state[Nb*i+j] & 0x0f;
                state[Nb*i+j] = inv_s_box[16*row+col];
            }
        }
    }

    /*
     * Function used in the Key Expansion routine that takes a four-byte
     * input word and applies an S-box to each of the four bytes to
     * produce an output word.
     */
    void sub_word(uint8_t *w) {

        uint8_t i;

        for (i = 0; i < 4; i++) {
            w[i] = s_box[16*((w[i] & 0xf0) >> 4) + (w[i] & 0x0f)];
        }
    }

    /*
     * Function used in the Key Expansion routine that takes a four-byte
     * word and performs a cyclic permutation.
     */
    void rot_word(uint8_t *w) {

        uint8_t tmp;
        uint8_t i;

        tmp = w[0];

        for (i = 0; i < 3; i++) {
            w[i] = w[i+1];
        }

        w[3] = tmp;
    }


    //////////////////////////////////////////////////////////
    //////////////////////////////////////////////////////////

    /*
     * Key Expansion
     */
    void key_expansion(uint8_t *key) {

        uint8_t tmp[4];
        uint8_t i;
        uint8_t len = Nb*(Nr+1);

        if( w ) { delete [] w; w = NULL; }
        w = new uint8_t[len*4];

        for (i = 0; i < Nk; i++) {
            w[4*i+0] = key[4*i+0];
            w[4*i+1] = key[4*i+1];
            w[4*i+2] = key[4*i+2];
            w[4*i+3] = key[4*i+3];
        }

        for (i = Nk; i < len; i++) {
            tmp[0] = w[4*(i-1)+0];
            tmp[1] = w[4*(i-1)+1];
            tmp[2] = w[4*(i-1)+2];
            tmp[3] = w[4*(i-1)+3];

            if (i%Nk == 0) {

                rot_word(tmp);
                sub_word(tmp);
                coef_add(tmp, Rcon(i/Nk), tmp);

            } else if (Nk > 6 && i%Nk == 4) {

                sub_word(tmp);

            }

            w[4*i+0] = w[4*(i-Nk)+0]^tmp[0];
            w[4*i+1] = w[4*(i-Nk)+1]^tmp[1];
            w[4*i+2] = w[4*(i-Nk)+2]^tmp[2];
            w[4*i+3] = w[4*(i-Nk)+3]^tmp[3];
        }
    }

    void cipher(uint8_t *in, uint8_t *out) {

        uint8_t *state;
        uint8_t r, i, j;

        state = new uint8_t[4*Nb];

        for (i = 0; i < 4; i++) {
            for (j = 0; j < Nb; j++) {
                state[Nb*i+j] = in[i+4*j];
            }
        }

        add_round_key(state, w, 0);

        for (r = 1; r < Nr; r++) {
            sub_bytes(state);
            shift_rows(state);
            mix_columns(state);
            add_round_key(state, w, r);
        }

        sub_bytes(state);
        shift_rows(state);
        add_round_key(state, w, Nr);

        for (i = 0; i < 4; i++) {
            for (j = 0; j < Nb; j++) {
                out[i+4*j] = state[Nb*i+j];
            }
        }

        delete [] state;
    }

    void inv_cipher(uint8_t *in, uint8_t *out) {

        uint8_t *state;
        uint8_t r, i, j;

        state = new uint8_t[4*Nb];

        for (i = 0; i < 4; i++) {
            for (j = 0; j < Nb; j++) {
                state[Nb*i+j] = in[i+4*j];
            }
        }

        add_round_key(state, w, Nr);

        for (r = Nr-1; r >= 1; r--) {
            inv_shift_rows(state);
            inv_sub_bytes(state);
            add_round_key(state, w, r);
            inv_mix_columns(state);
        }

        inv_shift_rows(state);
        inv_sub_bytes(state);
        add_round_key(state, w, 0);

        for (i = 0; i < 4; i++) {
            for (j = 0; j < Nb; j++) {
                out[i+4*j] = state[Nb*i+j];
            }
        }

        delete [] state;
    }

}; // end of AES_Contex



////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////

AES_CONTEX AES_setKey(AES_KEY& key)
{
    int uKeyLen;

    int kLen = key.size();
    if( kLen <= 16 ) {
        uKeyLen = 16;
    } else if( kLen > 16 && kLen <= 24 ) {
        uKeyLen = 24;
    } else {
        uKeyLen = 32;
    }

    key.resize(uKeyLen, 0);

    // create AES contex & expension key
    AES_Contex *_ctx = new AES_Contex;

    switch ( uKeyLen ) {
    default:
    case 16: _ctx->Nk = 4; _ctx->Nr = 10; break;
    case 24: _ctx->Nk = 6; _ctx->Nr = 12; break;
    case 32: _ctx->Nk = 8; _ctx->Nr = 14; break;
    }

    _ctx->key_expansion((uint8_t*) key.data());

    return (AES_CONTEX) _ctx;
}

AES_CONTEX AES_setKey(const std::string& key_)
{
    AES_KEY key = pi::crypto::str2vec(key_);
    return AES_setKey(key);
}

int AES_freeKey(AES_CONTEX ctx)
{
    AES_Contex *_ctx = (AES_Contex*) ctx;

    if( _ctx != NULL ) {
        delete _ctx;
    } else {
        return -1;
    }

    return 0;
}


int AES_encodeMsg(AES_CONTEX ctx, const std::vector<uint8_t>& msgIn, std::vector<uint8_t>& msgOut)
{
    AES_Contex *_ctx = (AES_Contex*) ctx;

    if( _ctx == NULL ) return -1;

    // prepare buffer
    int np = 4*_ctx->Nb;
    int n = msgIn.size();

    int k = n / np;
    if( n % np ) k ++;

    std::vector<uint8_t> buf = msgIn;
    buf.resize(k*np, 0);
    msgOut.resize(k*np, 0);

    // do cipher
    uint8_t *p1, *p2;
    p1 = (uint8_t*) buf.data();
    p2 = (uint8_t*) msgOut.data();

    for(int i=0; i<k; i++) {
        _ctx->cipher(p1, p2);

        p1 += np;
        p2 += np;
    }

    return 0;
}

int AES_decodeMsg(AES_CONTEX ctx, const std::vector<uint8_t>& msgIn, std::vector<uint8_t>& msgOut)
{
    AES_Contex *_ctx = (AES_Contex*) ctx;

    if( _ctx == NULL ) return -1;

    // prepare buffer
    int np = 4*_ctx->Nb;
    int n = msgIn.size();

    int k = n / np;
    if( n % np ) k ++;

    std::vector<uint8_t> buf = msgIn;
    buf.resize(k*np, 0);
    msgOut.resize(k*np, 0);

    // do cipher
    uint8_t *p1, *p2;
    p1 = (uint8_t*) buf.data();
    p2 = (uint8_t*) msgOut.data();

    for(int i=0; i<k; i++) {
        _ctx->inv_cipher(p1, p2);

        p1 += np;
        p2 += np;
    }

    return 0;
}


}} // end of namespace pi::crypto
